Method:1. Thoroughly clean the leg of lamb and prick all over with a fork.2. Prepare a mixture of salt, red chilli powder, ginger and garlic pastes, mace and cardamom powders and lemon juice.3. Marinate the leg in this mix for 2 hours.4. Pour the vinegar and rum over the lamb.5. Place leg on a baking tray and pour over 1 litre/4 cups water.6. Bake in an oven at 350F for 1 1/2 hours turning the leg two or three times to ensure it cooks evenly.7. Once water dries out remove from tray. Baste with oil and grill till well done all over.8. Garnish with onion rings and sliced tomato. Sprinkle chaat masala and serve hot.